The investigators will recruit two populations of 40 patients each. The first population will be patients with known stable coronary heart disease. They will have previously documented and angiographically proven coronary artery disease (≥70% luminal stenosis of a major epicardial vessel). The second population will be patients with a recent (within 30 days) acute myocardial infarction defined by the Universal definition of myocardial infarction. The culprit plaque will be defined according to the invasive coronary angiogram appearances, electrocardiogram and clinical features by two cardiologists blinded to the results of positron emission tomography.